Vehicle wheel alignment apparatus and method

Abstract

Noncontact sensors project fanned or structured light onto the tire, while the wheel is rotated, to illuminate at least two contour lines on the surface of the tire. the contour lines are read by video cameras, positioned offset from the optical plane of the structured light, to allow triangulation in determining the spatial position of the contour lines. Radially equivalent points are selected from each contour line by an algorithm which ignores the effects of any raised lettering on the tire sidewalls. Control of the video cameras and processing of the video data is performed by parallel processor-based computer system coordinated by sequencer circuit.

What is claimed is: 
     
       1. A system for measuring a predetermined alignment characteristic of a wheel defining a plane normal to the axis of the axle of the vehicle on which the wheel is mounted, comprising: means for establishing a predetermined target associated with the wheel that defines the position and orientation of said plane in three-dimensional space;   optical sensor means having associated therewith a field of view and being positioned relative to wheel so that said target is located within said field of view for creating an image of said target and converting said image to corresponding electrical signals;   processor means for processing said electrical signals, determining therefrom the position and orientation of said plane in three-dimensional space relative to a predefined datum, and calculating therefrom said predetermined alignment characteristic of said wheel.   
     
     
       2. A method of measuring a predetermined alignment characteristic of a wheel defining a plane normal to the axis of the axle of the vehicle on which the wheel is mounted, comprising the steps of: optically creating a predefined target associated with said wheel that defines the position and orientation of said plane;   optically sensing the position and orientation of said target and determining therefrom the position and orientation of said plane in three-dimensional space relative to a predefined datum; and   calculating therefrom said predetermined alignment characteristic of said wheel.   
     
     
       3. A system for measuring a predetermined alignment characteristic of a wheel defining a plane normal to the axis of an axle of the vehicle on which the wheel is mounted comprising: means for optically creating a predefined target associated with said wheel that defines the position and orientation of said plane;   optical sensing means for measuring the position in three-dimensional space of said target; and   processor means responsive to said optical sensing means for calculating said predetermined alignment characteristic of said wheel.